python3 异步 asyncio 动态添加任务

asyncio.run_forever()下动态添加任务

方法一、asyncio.run_coroutine_threadsafe(coroutine, loop)

方法二、asyncio.call_soon_threadsafe(callback, *args, context=None)

 

方法一、实例run_coroutine_threadsafe

通过添加新的coroutin对象，放入loop内，动态添加。（爬虫正解）

import asyncio
import time

from threading import Thread


def start_loop(loop):
    asyncio.set_event_loop(loop)
    print("start loop", time.time())
    loop.run_forever()


async def do_some_work(x):
    print('start {}'.format(x))
    await asyncio.sleep(x)
    print('Done after {}s'.format(x))


new_loop = asyncio.new_event_loop()
t = Thread(target=start_loop, args=(new_loop,))
t.start()

asyncio.run_coroutine_threadsafe(do_some_work(6), new_loop)
asyncio.run_coroutine_threadsafe(do_some_work(4), new_loop)

方法二、实例call_soon_threadsafe

如果是io操作，就会相当于变成线程去阻塞执行添加进去的函数，密集型则没关系。

import asyncio
import time
from threading import Thread


def start_loop(loop):
    asyncio.set_event_loop(loop)
    print("start loop")
    loop.run_forever()


def more_work(x):
    print('start work {}'.format(x))
    time.sleep(x)
    print('Finished work {}'.format(x))


new_loop = asyncio.new_event_loop()
t = Thread(target=start_loop, args=(new_loop,))
t.start()

new_loop.call_soon_threadsafe(more_work, 6)
new_loop.call_soon_threadsafe(more_work, 3)